This application is related to subject matter disclosed in: A1) U.S. provisional Application No. 60/111,484 entitled “An all-fiber-optic modulator” filed Dec. 7, 1998 in the names of Kerry J. Vahala and Amnon Yariv, said provisional application being hereby incorporated by reference in its entirety as if fully set forth herein;                A2) U.S. application Ser. No. 09/454,719 entitled “Resonant optical wave power control devices and methods” filed Dec. 7, 1999 in the names of Kerry J. Vahala and Amnon Yariv, said application being hereby incorporated by reference in its entirety as if fully set forth herein;        A3) U.S. provisional Application No. 60/108,358 entitled “Dual tapered fiber-microsphere coupler” filed Nov. 13, 1998 in the names of Kerry J. Vahala and Ming Cai, said provisional application being hereby incorporated by reference in its entirety as if fully set forth herein;        A4) U.S. Application Ser. No. 09/440,311 entitled “Resonator fiber bi-directional coupler” filed Nov. 12, 1999 in the names of Kerry J. Vahala, Ming Cai, and Guido Hunziker, said application being hereby incorporated by reference in its entirety as if fully set forth herein; and        A5) U.S. provisional Application No. 60/183,499 entitled “Resonant optical power control devices and methods of fabrication thereof” filed Feb. 17, 2000 in the names of Peter C. Sercel and Kerry J. Vahala, said provisional application being hereby incorporated by reference in its entirety as if fully set forth herein.        A6) U.S. provisional application entitled “Fiber-optic waveguides for evanescent optical coupling and methods of fabrication and use thereof”, filed Aug. 18, 2000 in the names of Peter C. Sercel, Guido Hunziker, and Robert B. Lee, Application Ser. No. 60/226,147, said provisional application being hereby incorporated by reference in its entirety as if fully set forth herein.        A7) U.S. provisional Application No. 60/257,248 entitled “Modulators for resonant optical power control devices and methods of fabrication and use thereof” filed Dec. 21, 2000 in the names of Oskar J. Painter, Peter C. Sercel, Kerry J. Vahala, and Guido Hunziker, said provisional application being hereby incorporated by reference as if fully set forth herein.        A8) U.S. provisional application entitled “Waveguides and resonators for integrated optical devices and methods of fabrication and use thereof”, filed Dec. 21, 2000 in the name of Oskar J. Painter, Application Ser. No. 60/257,218, said provisional application being hereby incorporated by reference as if fully set forth herein.        A9). U.S. utility patent Application No. 09/788,303 entitled “Cylindrical processing of a optical media” filed concurrently with the present application in the names of Peter C. Sercel, Kerry J. Vahala, David W. Vernooy, and Guido Hunziker, said application being hereby incorporated by reference as if fully set forth herein.        A10). U.S. utility patent Application No. 09/788,331 entitled “Fiber-ring optical resonators” filed concurrently with the present application in the names of Peter C. Sercel, Kerry J. Vahala, David W. Vernooy, Guido Hunziker, and Robert B. Lee, said application being hereby incorporated by reference as if fully set forth herein.        A12). U.S. utility patent Application No. 09/788,301 entitled “Resonant optical power control device assemblies” filed concurrently with the present application in the names of Peter C. Sercel, Kerry J. Vahala, David W. Vernooy, Guido Hunziker, Robert B. Lee, and Oskar J. Painter, said application being hereby incorporated by reference as if fully set forth herein.        A13) U.S. provisional Application No. 60/170,074 entitled “Optical routing/switching based on control of waveguide-ring resonator coupling”, filed Dec. 9, 1999 in the name of Amnon Yariv, said provisional application being hereby incorporated by reference in its entirety as if fully set forth herein.        A14) U.S. Pat. No. 6,052,495 entitled “Resonator modulators and wavelength routing switches” issued Apr. 18, 2000 in the names of Brent E. Little, James S. Foresi, and Hermann A. Haus, said patent being hereby incorporated by reference in its entirety as if fully set forth herein.        A15) U.S. Pat. No. 6,101,300 entitled “High efficiency channel drop filter with absorption induced on/off switching and modulation” issued Aug. 8, 2000 in the names of Shanhui Fan, Pierre R. Villeneuve, John D. Joannopoulos, Brent E. Little, and Hermann A. Haus, said patent being hereby incorporated by reference in its entirety as if fully set forth herein. This application is also related to subject matter disclosed in the following 17 publications, each of said 17 publications being hereby incorporated by reference in its entirety as if fully set forth herein:        P1) Ming Cai, Guido Hunziker, and Kerry Vahala, “Fiber-optic add-drop device based on a silica microsphere whispering gallery mode system”, IEEE Photonics Technology Letters Vol. 11 686 (1999);        P2) J. C. Knight, G. Cheung, F. Jacques, and T. A. Birks, “Phased-matched excitation of whispering gallery-mode resonances by a fiber taper”, Optics Letters Vol. 22 1129 (1997);        P3) Hiroshi Wada, Takeshi Kamijoh, and Yoh Ogawa, “Direct bonding of InP to different materials for optical devices”, Proceedings of the third international symposium on semiconductor wafer bonding: Physics and applications, Electrochemical Society Proceedings, Princeton N.J., Vol. 95-7, 579-591 (1995).        P4) R. H. Horng, D. S. Wuu, S. C. Wei, M. F. Huang, K. H. Chang, P. H. Liu, and K. C. Lin, “AlGaInP/AuBe/glass light emitting diodes fabricated by wafer-bonding technology”, Appl. Phys. Letts. Vol. 75(2)154 (1999).        P5) Y. Shi, C. Zheng, H. Zhang, J. H. Bechtel, L. R. Dalton, B. B. Robinson, W. Steier, “Low (sub-1-volt) halfwave voltage polymeric electro-optic modulators achieved by controlling chromophore shape”, Science Vol. 288, 119 (2000).        P6) E. L. Wooten, K. M. Kissa, and A. Yi-Yan, “A review of lithium niobate modulators for fiber-optic communications systems”, IEEE J. Selected Topics in Quantum Electronics, Vol. 6(1), 69 (2000).        P7) D. L. Huffaker, H. Deng, Q. Deng, and D. G. Deppe, “Ring and stripe oxide-confined vertical-cavity surface-emitting lasers”, Appl. Phys. Lett., Vol. 69(23), 3477 (1996).        P8) Serpenguzel, S. Arnold, and G. Griffel, “Excitation of resonances of microspheres on an optical fiber”, Opt. Lett. Vol. 20, 654 (1995);        P9) F. Treussart, N. Dubreil, J. C. Knight, V. Sandoghar, J. Hare, V. Lefevre-Seguin, J. M. Raimond, and S. Haroche, “Microlasers based on silica microspheres”, Ann. Telecommun. Vol. 52, 557 (1997); and        P10) M. L. Gorodetsky, A. A. Savchenkov, V. S. Ilchenko, “Ultimate Q of optical microsphere resonators”, Optics Letters, Vol. 21, 453 (1996).        P11) Ming Cai, Oskar Painter, and Kerry J. Vahala, “Observation of critical coupling in a fiber taper to a silica-microsphere whispering-gallery mode system”, Physical Review Letters, Vol. 85(1) 74 (2000).        P12) Andreas Othonos, “Fiber Bragg gratings”, Rev. Sci. Instrum. Vol. 68(12) 4309 (1997).        P13) B. A. Little, S. T. Chu, H. A. Haus, J. Foresi, and J.-P. Laine, “Microring channel dropping filters”, J. Lightwave Technology Vol. 15 998 (1997).        P14) Giora Griffel, “Synthesis of optical filters using ring resonator arrays”, IEEE Photonics Technology Letts. Vol. 12 810 (2000).        P15) G. Metz et al., <<Bragg grating formation and germanosilicate fiber photosensitivity”, SPPIE Vol 1516 Int. Workshop on Photoinduced Self-organization in Optical Fiber (1991).        P16) T. Erdogan, V. Mizrahi, P. J. Lemaire, and D. Monroe, “Decay of UV-induced fiber Bragg gratings”, J. Appl. Phys. Vol. 76 73 (1994).        P17) Wei Xu, Mank Janos, Danny Wong, Simon Fleming, “Thermal poling of boron-codoped germanosilicate”, IEICE Trans. Electron., Vol E82-C(8) 1549 (1999).        
Optical fiber and propagation of high-data-rate optical pulse trains therethrough has become the technology of choice for high speed telecommunications. Wavelength division multiplexing (WDM) techniques are now commonly used to independently transmit a plurality of signals over a single optical fiber, independent data streams being carried by optical fields propagating through the optical fiber at a slightly differing optical carrier wavelengths (i.e., signal channels). WDM techniques include dense wavelength division multiplexing (DWDM) schemes, wherein the frequency spacing between adjacent signal channels may range from a few hundred GHz down to a few GHz. A propagating mode of a particular wavelength must be modulated, independently of other propagating wavelengths, in order to carry a signal. A signal carried by a particular wavelength channel must be independently accessible for routing from a particular source to a particular destination. These requirements have previously required complex and difficult-to-manufacture modulating and switching devices requiring extensive active alignment procedures during fabrication/assembly, and as a result are quite expensive. Such devices may require conversion of the optical signals to electronic signals and/or vice versa, which is quite power consuming and inefficient. In the patent applications A1 through A14 cited above a new approach has been disclosed for controlling optical power transmitted through an optical fiber that relies on the use of resonant circumferential-mode optical resonators, or other optical resonators, for direct optical coupling to a propagating mode of an optical fiber resonant with the optical resonator, thereby enabling wavelength-specific modulation, switching, and routing of optical signals propagating through the optical fiber. A thorough discussion of the features and advantages of such optical power control devices and techniques, as well as methods of fabrication, may be found in these applications, already incorporated by reference herein.
One important element of these latter devices is optical coupling between a fiber-optic waveguide and a circumferential-mode optical resonator. The circumferential-mode optical resonator provides wavelength specificity, since only propagating optical modes substantially resonant with the circumferential-mode optical resonator will be significantly affected by the device. A fiber-optic waveguide for transmitting the optical signal through the control device is typically provided with an evanescent optical coupling segment, where an evanescent portion of the propagating optical mode extends beyond the waveguide and overlaps a portion of a circumferential optical mode of the circumferential-mode optical resonator, thereby optically coupling the circumferential-mode optical resonator and the fiber-optic waveguide. The evanescent optical coupling segment may take one of several forms, including an optical fiber taper, D-shaped optical fiber, an optical fiber with a saddle-shaped concavity in the cladding layer, and/or other functionally equivalent configurations. These are discussed in detail in patent applications A1 through A7 cited herein.
The circumferential-mode optical resonator structure may comprise a glass micro-sphere or micro-disk, a fiber-ring resonator, a semiconductor ring/waveguide, or other functionally equivalent structure, described in detail in earlier-cited applications A1 through A8. A high-Q circumferential-mode optical resonator supports relatively narrow-linewidth resonant circumferential optical modes (i.e., having a linewidth consistent with typical linewidths of a WDM system, TDM system, or other optical data transmission system), which in an optical power control device may optically couple to propagating optical modes of the fiber-optic waveguide of substantially resonant optical wavelength. The circumferential-mode optical resonator therefore provides the wavelength selectivity of the optical power control device. Non-resonant propagating optical signals pass by the circumferential-mode optical resonator relatively undisturbed, and are transmitted through the device. The effect of the device on a substantially resonant signal channels depends on the nature of the control device.
A resonant optical filter may be constructed by coupling a second optical waveguide to the resonator to a similar degree that the fiber-optic waveguide is optically coupled to the resonator. In this case a critical-coupling condition exists between the resonator and fiber-optic waveguide, and for this condition substantially all of the resonant optical signal will be transferred from the fiber-optic waveguide to the second waveguide. Such a configuration is useful for constructing channel slicer/interleavers or channel add/drop filters for WDM and/or WDM optical transmission systems. Such a device enables wavelength-specific routing of one or more resonant signal channels among group of signal channels.
Alternatively, a resonant optical modulator or switch may be constructed by providing the circumferential-mode optical resonator with an optical loss mechanism that may be actively controlled or modulated. By modulating the resonator loss between critical-coupling and either over- or under-coupling, the transmission of a resonant signal channel may be selectively modulated between near-zero transmission and non-zero transmission. Since the circumferential-mode optical resonator provides wavelength(i.e., signal channel) specificity, the optical loss mechanism need not be wavelength specific.
It is therefore desirable to provide resonant optical power control devices for providing wavelength specific modulation of an optical signal channel. It is therefore desirable to provide resonant optical power control devices for providing wavelength specific routing of an optical signal channel. It is desirable to provide fiber-ring resonators for incorporation into resonant optical power control devices as the circumferential mode optical resonator. It is therefore desirable to provide cylindrical processing methods for fabricating components for optical power control devices, including fiber-ring resonators. It is therefore desirable to provide device assembly methods and configurations for resonant optical power control devices.